Expanded T lymphocytes in the cerebrospinal fluid of multiple sclerosis patients are specific for Epstein-Barr-virus-infected B cells

Immunology of multiple sclerosis: an update

PURPOSE OF REVIEW

The immunological processes that lead to multiple sclerosis (MS) and occur during the progressive phase of the disease are manifold and still not well understood. This review summarizes new insights on this topic that were gained through recent studies with diverse scientific approaches.

RECENT FINDINGS

While genetic risk clearly contributes to MS, external factors play a key role in its pathogenesis as well. Epstein-Barr virus infection correlates significantly with MS risk and seems to be a major causal factor. Even though our knowledge on the human gut microbiome and its connection to the central nervous system is far from being complete, several studies have proven that the gut-brain axis influences neuroinflammation and disease progression in MS. It has become much clearer that MS is not solely a T cell-mediated disease but is also strongly driven by B cells and pathogenic antibodies. Beyond the peripheral immune cells, glial cells and their interactions with neurons are important players contributing to disease activity and progression in MS.

SUMMARY

Taken together, recent publications on immunological processes in the context of MS implicate a multitude of noncanonical mechanisms that need to be further explored regarding their interplay and contribution to the degenerative course of the disease.

Epstein-Barr virus pathogenesis and emerging control strategies

Sixty years after its discovery as the first human tumour virus, Epstein-Barr virus (EBV)-specific therapies and vaccines have entered clinical trials. These might not only be applicable for EBV-associated malignancies, where the virus was originally discovered, but also to immunopathologies, including the autoimmune disease multiple sclerosis, which might be triggered in susceptible individuals by primary EBV infection. This Review discusses the surprisingly large spectrum of diseases that EBV seems to cause, as well as which of these might be treated by the therapeutic approaches that are currently being developed or are already clinically applied. New pharmacological inhibitors, antibody therapies, adoptive T cell therapies and active vaccinations are beginning to offer possibilities to target the various EBV infection programmes that are associated with different diseases. These novel developments might allow us to specifically target EBV rather than its host cells in virus-associated pathologies.

Multiple sclerosis and infection: history, EBV, and the search for mechanism

SUMMARYInfection has long been hypothesized as the cause of multiple sclerosis (MS), and recent evidence for Epstein-Barr virus (EBV) as the trigger of MS is clear and compelling. This clarity contrasts with yet uncertain viral mechanisms and their relation to MS neuroinflammation and demyelination. As long as this disparity persists, it will invigorate virologists, molecular biologists, immunologists, and clinicians to ascertain how EBV potentiates MS onset, and possibly the disease's chronic activity and progression. Such efforts should take advantage of the diverse body of basic and clinical research conducted over nearly two centuries since the first clinical descriptions of MS plaques. Defining the contribution of EBV to the complex and multifactorial pathology of MS will also require suitable experimental models and techniques. Such efforts will broaden our understanding of virus-driven neuroinflammation and specifically inform the development of EBV-targeted therapies for MS management and, ultimately, prevention.

Antibody reactivity against EBNA1 and GlialCAM differentiates multiple sclerosis patients from healthy controls

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system (CNS), which is linked to Epstein-Barr virus (EBV) infection, preceding the disease. The molecular mechanisms underlying this connection are only partially understood. We previously described molecular mimicry between the EBV transcription factor EBV nuclear antigen 1 (EBNA1) and three human CNS proteins: anoctamin-2 (ANO2), alpha-B crystallin (CRYAB), and glial cellular adhesion molecule (GlialCAM). Here, we investigated antibody responses against EBNA1 and GlialCAM in a large cohort of 650 MS patients and 661 matched population controls and compared them to responses against CRYAB and ANO2. We confirmed that elevated IgG responses against EBNA1 and all three CNS-mimic antigens associate with increased MS risk. Blocking experiments confirmed the presence of cross-reactive antibodies and molecular mimicry between EBNA1 and GlialCAM, and accompanying antibody responses against adjacent peptide regions of GlialCAM suggest epitope spreading. Antibody responses against EBNA1, GlialCAM, CRYAB, and ANO2 are elevated in MS patients carrying the main risk allele HLA-DRB1*15:01, and combinations of HLA-DRB1*15:01 with anti-EBNA1 and anti-GlialCAM antibodies increase MS risk significantly and in an additive fashion. In addition, antibody reactivities against more than one EBNA1 peptide and more than one CNS-mimic increase the MS risk significantly but modestly. Overall, we show that molecular mimicry between EBNA1 and GlialCAM is likely an important molecular mechanism contributing to MS pathology.

Detection of human brain cancers using genomic and immune cell characterization of cerebrospinal fluid through CSF-BAM

Patients who have radiographically detectable lesions in their brain or other symptoms compatible with brain tumors pose challenges for diagnosis. The only definitive way to diagnose such patients is through brain biopsy, an obviously invasive and dangerous procedure. Here we present a new workflow termed "CSF-BAM" that simultaneously identifies B cell or T cell receptor rearrangements, A neuploidy, and M utations using PCR-mediated amplification of both strands of the DNA from CSF samples. We first describe the details of the molecular genetic assessments and then establish thresholds for positivity using training sets of libraries from patients with or without cancer. We then applied CSF-BAM to an independent set of 206 DNA samples from patients with common, aggressive cancer types as well as other forms of brain cancers. Among the 126 samples from patients with the most common aggressive cancer types (high grade gliomas, medulloblastomas, or metastatic cancers to the brain), the sensitivity of detection was >81%. None of 33 CSF-BAM assays (100% specificity, 90% to 100% credible interval) were positive in CSF samples from patients without brain cancers. The sensitivity of CSF-BAM was considerably higher than that achieved with cytology. CSF-BAM provides an integrated multi-analyte approach to identify neoplasia in the central nervous system, provides information about the immune environment in patients with or without cancer, and has the potential to inform the subsequent management of such patients.

Statement of significance

There is a paucity of technologies beyond surgical biopsy that can accurately diagnose central nervous system neoplasms. We developed a novel, sensitive and highly specific assay that can detect brain cancers by comprehensively identifying somatic mutations, chromosomal copy number changes, and adaptive immunoreceptor repertoires from samples of cerebrospinal fluid.

Choroid Plexus as a Mediator of CNS Inflammation in Multiple Sclerosis

The pathophysiology of multiple sclerosis (MS) remains poorly understood despite decades of tremendous research efforts. Advances in neuroradiography coupled with availability of unbiased approaches including spatial transcriptomics, proteomics, metabolomics, and lipidomics that are compatible with brain and fluid specimens from patients raise hope that discovery of novel disease drivers is on the horizon. Once thought to be little more than salty bathwater, our modern understanding of cerebrospinal fluid (CSF) suggests the CSF as a compelling, critical regulator of brain function in health and disease. Recent studies in the field have reinvigorated interest in CSF as a medium to better understand MS and to deliver disease-modifying therapies. In turn, the choroid plexus, an epithelial tissue located within each brain ventricle that regulates CSF and forms a key blood-CSF barrier, is uniquely positioned to orchestrate neuroinflammation associated with MS. In this perspective review, we will discuss what is known about the choroid plexus as a conductor of immune responses and how it may propagate neuroinflammation associated with MS via the CSF.

Global perspectives on the contribution of B cells to multiple sclerosis: an in-depth examination and evaluation

Background

Multiple sclerosis (MS) is a chronic, progressive autoimmune disease, with increasing attention on the role of B cells in its pathogenesis. Despite this growing interest, a comprehensive analysis of research trends and emerging foci on B cells in MS is currently lacking. In this research, we utilize a bibliometric approach to visualize and analyze research trends and focal points in this field, offering a valuable reference for future mechanistic studies in MS.

Methods

We retrieved bibliometric data from the Web of Science Core Collection (WOSCC) for articles published between 2014 and 2023. VOSviewer 1.6.18 and CiteSpace 5.7R3 were used for co-authorship, co-occurrence, and citation analyses to identify key researchers, institutions, countries, and emerging themes in B cell research related to MS.

Results

The analysis examined 5,578 articles published in 1,041 journals by 5,337 institutions globally. The United States leads in publication output, with Amit Bar-Or identified as the most influential author, and Frontiers in Immunology as the top journal in the field. Research has increasingly focused on the complex role of B cells in MS, particularly their involvement in the central nervous system (CNS) and mechanisms of anti-B cell therapy. Recent trends point to a growing focus on meningeal inflammation, kinase inhibitors, and Epstein-Barr virus, signaling a shift in research priorities.

Conclusion

This bibliometric analysis highlights pivotal research trends, key contributors, and emerging areas of interest in B cell research in MS from 2013 to 2024. The findings underscore the growing recognition of the multifaceted role of B cells in MS pathogenesis, particularly their involvement in the CNS compartment and the potential of targeted therapies. The study identifies meningeal inflammation, Epstein-Barr virus infection, and kinase inhibitors as promising avenues for future research. The analyses driving the in-depth exploration of B cell mechanisms in MS and the development of novel diagnostic and therapeutic strategies provide researchers in the MS field with a comprehensive and objective perspective, serving as a valuable reference for accelerating the translation of basic research findings into clinical applications.

Antigen specificity of clonally-enriched CD8+ T cells in multiple sclerosis

CD8+ T cells are the dominant lymphocyte population in multiple sclerosis (MS) lesions where they are highly clonally expanded. The clonal identity, function, and antigen specificity of CD8+ T cells in MS are not well understood. Here we report a comprehensive single-cell RNA-seq and T cell receptor (TCR)-seq analysis of the cerebrospinal fluid (CSF) and blood from a cohort of treatment-naïve MS patients and control participants. A small subset of highly expanded and activated CD8+ T cells were enriched in the CSF in MS that displayed high activation, cytotoxicity and tissue-homing transcriptional profiles. Using a combination of unbiased and targeted antigen discovery approaches, MS-derived CD8+ T cell clonotypes recognizing Epstein-Barr virus (EBV) antigens and multiple novel mimotopes were identified. These findings shed vital insight into the role of CD8+ T cells in MS and pave the way towards disease biomarkers and therapeutic targets.

Enhanced and cross-reactive in vitro memory B cell response against Epstein-Barr virus nuclear antigen 1 in multiple sclerosis

Multiple sclerosis (MS) is a prototypical autoimmune disease of the central nervous system (CNS). In addition to CD4+ T cells, memory B cells are now recognized as a critical cell type in the disease. This is underlined by the fact that the best-characterized environmental risk factor for MS is the Epstein-Barr virus (EBV), which can infect and persist in memory B cells throughout life. Several studies have identified changes in anti-EBV immunity in patients with MS. Examples include elevated titers of anti-EBV nuclear antigen 1 (EBNA1) antibodies, interactions of these with the MS-associated HLA-DR15 haplotype, and molecular mimicry with MS autoantigens like myelin basic protein (MBP), anoctamin-2 (ANO2), glial cell adhesion molecule (GlialCAM), and alpha-crystallin B (CRYAB). In this study, we employ a simple in vitro assay to examine the memory B cell antibody repertoire in MS patients and healthy controls. We replicate previous serological data from MS patients demonstrating an increased secretion of anti-EBNA1380-641 IgG in cell culture supernatants, as well as a positive correlation of these levels with autoantibodies against GlialCAM262-416 and ANO21-275. For EBNA1380-641 and ANO21-275, we provide additional evidence suggesting antibody cross-reactivity between the two targets. Further, we show that two efficacious MS treatments - natalizumab (NAT) and autologous hematopoietic stem cell transplantation (aHSCT) - are associated with distinct changes in the EBNA1-directed B cell response and that these alterations can be attributed to the unique mechanisms of action of these therapies. Using an in vitro system, our study confirms MS-associated changes in the anti-EBNA1 memory B cell response, EBNA1380-641 antibody cross-reactivity with ANO21-275, and reveals treatment-associated changes in the immunoglobulin repertoire in MS.

Multiple sclerosis and the intestine: Chasing the microbial offender

Multiple sclerosis (MS) affects more than 2.8 million people worldwide but the distribution is not even. Although over 200 gene variants have been associated with susceptibility, studies of genetically identical monozygotic twin pairs suggest that the genetic make-up is responsible for only about 20%-30% of the risk to develop disease, while the rest is contributed by milieu factors. Recently, a new, unexpected player has entered the ranks of MS-triggering or facilitating elements: the human gut microbiota. In this review, we summarize the present knowledge of microbial effects on formation of a pathogenic autoreactive immune response targeting the distant central nervous system and delineate the approaches, both in people with MS and in MS animal models, which have led to this concept. Finally, we propose that a tight combination of investigations of human patients with studies of suitable animal models is the best strategy to functionally characterize disease-associated microbiota and thereby contribute to deciphering pathogenesis of a complex human disease.

Altered EBV specific immune control in multiple sclerosis

Since the 1980s it is known that immune responses to the Epstein-Barr virus (EBV) are elevated in multiple sclerosis (MS) patients. Recent seroepidemiologial data have shown that this alteration after primary EBV infection identifies individuals with a more than 30-fold increased risk to develop MS. The mechanisms by which EBV infection might erode tolerance for the central nervous system (CNS) in these individuals, years prior to clinical MS onset, remain unclear. In this review I will discuss altered frequencies of EBV life cycle stages and their tissue distribution, EBV with CNS autoantigen cross-reactive immune responses and loss of immune control for autoreactive B and T cells as possible mechanisms. This discussion is intended to stimulate future studies into these mechanisms with the aim to identify candidates for interventions that might correct EBV specific immune control and/or resulting cross-reactivities with CNS autoantigens in MS patients and thereby ameliorate disease activity.